X-ray generators (also known as X-ray tubes) having stationary anodes, i.e. anodes that are immovably and in particular non-rotatably mounted in a vacuum enclosure of the X-ray generator, are known from various fields of X-ray technology, in particular the fields of imaging, radiation therapy or spectroscopy. In order to obtain correspondingly high performance, it is sometimes necessary to actively pass a cooling fluid through stationary anodes. Known stationary anodes have cooling ducts to carry the cooling fluid and are disposed such that in particular cooling fluid can be applied to an underside of a main anode body. The target which is able to be bombarded with electrons to produce X-radiation is typically disposed on the opposite upper side of the main anode body.
During operation, the target and the main anode body connected to the target material are at positive high voltage potential. Therefore, only coolants having little or no electrically conductivity tend to be used as cooling fluids. A cooling fluid used in practice is e.g. demineralized water (DM water). However, DM water has the property of binding ions from the environment. If the ion-enriched DM water comes into contact with in particular a main anode body consisting of copper, corrosion and progressive destruction and wash-out of the material will occur. This process is generally intensified by high temperatures and flow rates of the cooling fluid. For this reason, the surfaces coming into contact with the DM water, particularly heat exchange surfaces which are used to transfer heat to the cooling fluid flowing through the stationary anode, are often provided with a thin coating, i.e. a protective layer. However, the coating can be easily damaged in the event of mechanical stress particularly during assembly.
X-ray generators in which nozzles for cooling fluid are disposed at a distance from a main anode body over the entire circumference via stop elements are disclosed in U.S. Pat. Nos. 4,064,411 or 3,914,633, for example.
CH 663 114 describes a bottom-cooled anode body wherein an internal cooling chamber is delimited by an internal, conically shaped end face such that the axial width of the internal cooling chamber continuously decreases from the center to the edge in the radial direction.